Neighbors knew Robert Bowers as a truck driver who rarely hosted visitors but exchanged pleasantries as he came and went from his first-floor apartment in a complex in Baldwin, a suburb on the south side of Pittsburgh. His unremarkable facade made the role authorities say he played in the massacre that left 11 dead all the more chilling, they said.

“They showed his photo, and my stomach just dropped,” said Kerri Owens, who has lived next door to Bowers for two years, recalling the moment she saw his picture on the news. “I was sick to my stomach knowing he had been on the other side of the wall from me.”…

Owens said Bowers would say hello to her from time and time while outside smoking a cigarette. She never saw him with guests.

“We would have small talk, but he just seemed like a normal guy, and that is the scary part,” she said.